I came across an issue with my calibration process back a while ago and found that a bad master dark was to blame. This made me rethink my master frame thinking....again. I have downloaded, printed out, and reread the paper on Acquisition and Processing Master Calibration Frames a number of times and thought I had a good handle on it. Let me explain how I usually do this to see where I'm either wrong or right:
I take usually 100-200 bias frames on bad weather days. For my camera I was long ago advised that bias frames were sensitive to temperature on this model so I have always taken my biases at the same temperature which is easy as I always image at -20 and darks by the same temperature as well for the exposure times that I used being 900 and 1800 seconds. So I generally take 20-75 or so darks depending on weather to create my masters.
My flats are taken with a minimum of 16 per filter per side of pier (I use a rotator) meaning I have E/W side filter masters when finished. They do make a difference for me at least.
I calibrate the flats usually by using the settings as seen in the Master Calibration Frames Acquisition and Processing PDF found on the PI sight under Resources
https://pixinsight.com/tutorials/master-frames/index.html.
Recently I noticed that my master flats were showing pixel column defects in them which was then noticed on images when calibrated. So I stooped using the Master Bias frame and only now use the Master Dark set to Optimize which eliminated those column defects. My thinking is that since I'm not scaling the darks in my image calibration I shouldn't need the bias frames. So with my process do the instructions in the referenced PDF apply to my method? Do I actually need Master Bias frames at all?
Keep in mind that my flat frame exposures are under 2-6 seconds most for NB filters and just over 1 second for LRGB filters.
